退役工业固废填埋场地再利用的全寿命环境风险特征

Life cycle environmental risk characteristics of reuse of decommissioned industrial solid waste landfill sites

通过现场采样和过程模型模拟等方法研究了典型退役工业固废填埋场地(DISWL)原位开发条件下的健康风险及长期演化规律.结果表明,经过近20a的浸出和降解,86%的废物浸出浓度依然处于有害水平,70%的废物不宜直接作为建设用地土壤.直接作为建筑用地开发利用条件下,由于DISWL的性能退化会导致有害组分的浸出和渗漏增加,由此导致地下水水质超标概率经历从无(短期)到有(中期,个别物质如总氰化物T-CN和易释放氰化物F-CN),再到后期的较大概率超标(T-CN和F-CN)的渐变过程;同时,场地利用过程的健康风险也逐步增加,来自于As的致癌风险和自于T-CN的非致癌风险,分别超过风险可接受水平的81~179倍和55.32~224.3倍.上述结果提示DISWL场地开发再利用的风险评估和管控策略应重点考虑长期风险.对于长期风险不可接受的场地,通过降低废物中毒性物质的浸出浓度可实现长期风险可接受,并提出了相应浸出浓度限值的计算框架和方法.

This study studied the health risks and long-term evolution of the typical in-situ development of the decommissioned industrial solid waste landfill(DISWL)under in-situ development conditions through on-site sampling and process model simulation.The results demonstrated that 86%of the waste leaching concentration was harmful and 70%of the waste was not suitable for the direct use of construction land soil after nearly 20 years of leaching and degradation.Under the condition of direct use as construction land,the leakage risk of harmful components increased due to the degradation of DISWL performance,which result in the gradual process of the probability of groundwater quality exceeding the standard from none(short-term)to yes(medium-term,individual substances such as total cyanide T-CN and free cyanide F-CN),and then to a higher probability of exceeding the standard(T-CN and F-CN).Meanwhile,the health risks of the site utilization process also gradually increased,the carcinogenic risk from arsenic(As)and non carcinogenic risk from T-CN were 81~179 times and 55.32~224.3 times higher than the acceptable risk level,respectively.The above results suggest that the risk assessment and management strategy of DISWL site development and reuse should focus on long-term risks.For sites with unacceptable long-term risks,acceptable long-term risks can be achieved by reducing the leaching concentration of toxic substances in the waste,and proposes a calculation framework and method for the corresponding leaching concentration limits.